Sexual health charity the Terrence Higgins Trust (THT) will launch England's first ever national HIV testing week later this month.
The week, which will run from 23 to 30 November, is being co-ordinated through HIV Prevention England (HPE), which is a partnership of community organizations funded by the Department of Health to carry out national HIV prevention work in England among high risk groups.
The drive is part of HPE's Think HIV campaign, which aims to encourage gay and bisexual men to test more regularly for the virus.
According to THT, despite gay men being one of the groups most disproportionately affected by HIV, the virus remains undiagnosed in one in four.
Late diagnosis can lead to serious health problems, with men who have been tested after a point at which they should have started treatment nine times more likely to die within a year of the infection being identified than someone who tests in good time.
THT added that undiagnosed HIV is also a key factor driving the 'epidemic' among gay men, with the majority of onward transmission coming from men who are unaware that they have the infection.
'National HIV Testing Week gives us a great opportunity to remind men of the importance of regular testing,' said Paul Ward, deputy chief executive of THT.
'Terrence Higgins Trust recommends that sexually active gay and bi men test for HIV at least once a year, and more regularly if they have a high number of partners.'
However, Ward added that currently less than a quarter of men take an annual test.
He said: 'If the gay community can drive that figure upwards by testing more often, we will see a reduction in undiagnosed HIV, which in turn will begin to put the brakes on the spread of infection.
'We believe it is within our grasp to halt the spread of HIV, but solving this lies just as much with the gay community as it does with the government.
'That's why we need the whole community - venues, gay businesses and every one of us - to get behind this new initiative and turn a spotlight on HIV testing, not just during testing week but all year round.'